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Phase synchronizer and data reproducing apparatus

  • US 5,657,359 A
  • Filed: 11/02/1995
  • Issued: 08/12/1997
  • Est. Priority Date: 11/04/1994
  • Status: Expired due to Fees
First Claim
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1. A phase synchronizer comprising:

  • a first feedback circuit and a second feedback circuit,wherein said first feedback circuit includesa first phase comparator for generating a first pulse signal in accordance with a difference between phases of a first input signal and a first feedback signal;

    a first charge pump for converting the first pulse signal supplied from said first phase comparator to a first analog voltage signal;

    a first loop filter for removing high-frequency signal components from the first analog voltage signal output from said first charge pump, to output a first filtered analog voltage signal therefrom; and

    a first voltage-controlled oscillator, coupled to said first loop filter, for generating a first oscillation output signal having a first frequency which varies in accordance with said first filtered analog voltage signal, said first oscillation output signal being supplied as said first feedback signal to said first phase comparator, andwherein said second feedback circuit includesa second phase comparator for generating a second pulse signal in accordance with a difference between phases of a second input signal and a second feedback signal;

    a second charge pump for converting the second pulse signal supplied from said second phase comparator to a second analog voltage signal;

    a second loop filter for removing high-frequency signal components from the second analog voltage signal output from said second charge pump, to output a second filtered analog voltage signal therefrom; and

    a second voltage-controlled oscillator, coupled to said first loop filter as well as said second loop filter, for generating a second oscillation output signal having a second frequency which varies in accordance with said first and second filtered analog voltage signals, said second oscillation output signal being supplied as said second feedback signal to said second phase comparator and also as a final output of said phase synchronizer,wherein the second frequency of said second oscillation output signal changes to a greater extent with respect to a change in voltage of the first filtered analog voltage signal than with respect to a change in voltage of the second filtered analog voltage signal,wherein said second voltage-controlled oscillator includes odd-numbered stages of inverters and first and second variable resistor circuits intervened between said inverters, and said inverters and first and second variable resistor circuits being connected in a loop,wherein a resistance of said first variable resistor circuit is controlled to decrease a change of the resistance based on said second filtered analog voltage signal, while a resistance of said second variable resistor circuit is controlled to increase a change of the resistance based on said first filtered analog voltage signal,wherein said first and second variable resistor circuits respectively includes first and second transfer gates, each of which has at least on MOS transistor,wherein said second voltage-controlled oscillator further includes;

    a first bias circuit coupled to said first transfer gate, for applying a first bias voltage to said first transfer gate having a resistance as a function of the first bias voltage, said first bias voltage varying in accordance with said first filtered analog voltage signal supplied to said first bias circuit; and

    a second bias circuit coupled to said second transfer gate, for applying a second bias voltage to said second transfer gate having a resistance as a function of the second bias voltage, said second bias voltage varying in accordance with said second filtered analog voltage signal supplied to said second bias circuit; and

    wherein a change in said second bias voltage is larger than a change in said first bias voltage.

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